1. Field of the Invention
This invention relates to an apparatus and method for facilitating plasma processing and in particular chemical plasma enhanced vapor deposition, plasma polymerization or plasma treatment of barrier materials onto the interior surface of containers for providing an effective barrier against gas and/or water permeability
2. Description of the Related Art
Plastic containers frequently do not have the chemical and physical attributes for proper storage and/or handling of their intended contents, and so the plastic surface may be chemically modified or coated with a film that corrects these deficiencies and thereby adds value to the original plastic container. Examples of container attributes include barrier to gas and/or water vapor permeation and reactivity of surface with contents.
Of particular interest is plastic medical products such as evacuated blood collection tubes, syringes or specimen collection containers.
Evacuated plastic tubes are permeable to atmospheric gases and water vapor, and substantially lose vacuum over time. A consequence of lost vacuum is reduced draw volume and blood-to-additive ratio. Thus, there is need to improve the barrier properties of plastic tubes wherein certain performance standards would be met.
Methods for improving barrier properties of plastic containers include deposition of metals and metal oxide thin films from a vacuum deposition source such as plasma chemical vapor deposition, plasma polymerization, plasma sputtering, etc. The usual method of applying plasma deposition coatings or modifications to plastic containers has been to place the container or containers in a vacuum chamber containing low pressure process gases and electrodes for energizing a plasma. In most cases these processes apply the coating to the outside surfaces of the containers.
Therefore, a need exists for an improved method and apparatus for imparting a coating inside the surfaces of containers.